The cause was uncertain, but Mr. Miles had myriad health problems, including Parkinson’s disease and dementia, said his wife of 61 years, Gloria.

Mr. Miles was part historical sleuth, part preservationist, part bard. His films, which combined archival footage, still photographs and fresh interviews, were triumphs of curiosity and persistence in unearthing lost material about forgotten subjects.

His first important film, “Men of Bronze” (1977), was about the 369th Infantry Regiment, an all-black combat unit that the Army shipped overseas during World War I but, because of segregationist policies, fought under the flag of France. Serving with great distinction, the unit spent more time in the front-line trenches than any other American unit. Collectively, it was awarded the Croix de Guerre and came to be known as the Harlem Hellfighters and also the Black Rattlers.